2.5D IC packages are known in the art. In a 2.5D IC package, multiple dies or chips are typically mounted on a silicon interposer. The silicon interposer is responsible for the interconnections between the dies, as well as the external I/Os through the use of TSV (through substrate via or through silicon via) technology. Typically, the silicon interposer is then mounted onto a package substrate through C4 bumps.
However, TSV silicon interposers are relatively expensive. Therefore, it is desirable to provide an improved semiconductor package having an interposer without using TSV, while the interposer is still able to provide very fine pitch interconnections.
US 2015/0371965 A1 discloses a method for fabricating a high-density film for IC packages. One of the drawbacks of this prior art is that the temporary carrier I is removed before singulation of the circuitry film RDL I. Because of the lack of adequate mechanical support due to the removal of the temporary carrier I, the handling of the thin circuitry film RDL I becomes difficult and the production yield is therefore low.